Claude Tholosan's 1445 (?) treatise So That the Errors of Magicians and Witches has some pretty profound things to say about the Horned.
Admittedly, he does call him Diabolus, the Devil.
But lay that by for now.
He shows himself to each according to their desire...nor is he seen except by whom he wishes.
“He shows himself to each according to their desire.”
He's skin-strong, this one, a changer of shapes, and how you see him depends on you and your expectations. He shapes himself to you.
Relationship. It's all about relationship: his with you, yours with him.
What a god.
He shows himself to some as a man, to some as a woman, or some beast. Me, I saw a beautiful naked man with branching antlers.
To some he shows himself as Cernunnos, to some as Pan.
To Herb Sloane, founder of Our Lady of Endor Coven and the Ophitic Gnostic Cultus of Sathanas (ca. 1965)—as perhaps to M. Tholosan—he showed himself as the Devil.
One might even suppose, then—surely it is not beyond his capability—that to some he shows himself as Christ.
I say again: what a god.
“...Nor is he seen expect by whom he wishes.”